This invention relates generally to pneumatically operated motors and more specifically to a pneumatic motor assembly having throttling and reversing features.
The present invention is an improvement on my prior air motor reversing throttle shown and described in U.S. Pat. No. 5,423,350, the disclosure of which is incorporated herein by reference. My prior invention conveniently provides for throttling and forward and reverse operation of a pneumatic motor by simple pivoting movement of a single lever (31). Throttling and direction of movement can be actuated with one hand and can also entirely stop the motor. Pivoting movement of the lever in a first direction about an axis moves a valve (22) in a valve guide bore (12) in a housing to bring one of two valve passages (23 or 29) into registration with one of the corresponding passages (18 and 30 or 19 and 32) formed in the housing to drive the air motor in a counterclockwise or clockwise direction. In a middle or stop position of the valve, neither valve passage overlies either of the corresponding passages so there is no fluid communication through the valve to the motor. In addition, the lever can be moved to vary the amount of the passage (23 or 29) which overlaps the corresponding passage (30 or 32) the motor can be throttled to run at different speeds solely by manipulation of the lever.
The flow of air to the valve (22) is controlled by a plunger (21) which is spring biased to seat against a valve seat to block an air inlet passage from communicating with the valve. In order to move the plunger off of its seat to permit air to flow to the valve, a stem of the plunger is received in a V-shaped notch on one side of the plunger. As the valve slides transversely the notch moves relative to the stem so that the end of the stem is pushed rectilinearly (or xe2x80x9cperpendicularlyxe2x80x9d) to unseat the plunger and permit air to flow to the valve. The V-shape of the notch provides the same axial movement of the plunger for movement of the valve in either direction. Although my prior air motor reversing throttle works well and provides many conveniences for the operator, improvements can be made. It has been found that the interaction between the V-shaped notch and the plunger stem is such that return of the valve to the stop position is inhibited. Sometimes the force of the spring on the plunger is insufficient to move the valve and plunger to stop the motor when the lever is released. Moreover, the axial movement of the plunger can sometimes be difficult to achieve, requiring substantial force to be applied to the lever. The application of this force necessary to move the plunger off its seat can make it difficult to control the throttle with the lever.
Among the several objects and features of the present invention may be noted the provision of a pneumatic reversing motor assembly which can be actuated to start and run in forward and reverse directions by manipulation of a single lever; the provision of such motor assembly which can be throttled with the same lever; the provision of such a motor assembly which can be started and run in forward and reverse directions with minimal application of manual force to the lever; the provision of such a motor assembly which consistently returns to a stop position when manual force is released; the provision of such a motor assembly which is easy to use and economical to manufacture.
Generally, a reversible pneumatic motor assembly comprises a housing and a reversible motor in the housing. The housing includes an inlet connection for connecting the motor assembly to a source of pressurized air, an inlet passage extending inwardly into the housing from the inlet connection, a forward passage adapted for communicating with the inlet passage for delivering air to the motor for driving the motor in a forward direction and a reverse passage adapted for communicating with the inlet passage for delivering air to the motor for driving the motor in a reverse direction. A reversing valve assembly disposed in the housing between the inlet passage and the forward and reverse passages is capable of selectively controlling fluid communication between the inlet passage and the reversible motor by operation of an actuator mounted on the housing to selectively drive the motor in the forward and reverse directions. The reversing valve assembly comprises a tilt valve disposed in the inlet passage and receivable on a valve seat in the inlet passage to block the inlet passage. A spring biases the valve against the valve seat. A shuttle is located in the housing and connected to the actuator for transverse sliding motion in the housing. The shuttle and valve are mounted in the housing for movement upon actuation of the actuator between a first position in which the valve is tilted about an axis off of the valve seat and the shuttle is disposed to form a continuous air flow path from the inlet passage, through the shuttle and into the forward passage for driving the motor in the forward direction, a second position in which the valve is tilted about the axis off of the valve seat and the shuttle is disposed to form a continuous air flow path from the inlet passage, through the shuttle and into the reverse passage for driving the motor in the reverse direction, and a third position in which the valve seats on the valve seat to prevent flow of air from the inlet passage to the motor.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.